how to get waveform data when I play music in .net ios?

Question

how to get waveform data when I play music in .net ios?

mc 5,426

in .net android there is Visualizer but in .net ios there is not.

and I searched that there is InstallTapOnBus and how to get the data when it is playing?

Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Microsoft External Staff

Do you use AVAudioEngine and find the AVAudioPlayerNode? And then you call the installTapOnBus:bufferSize:format:block: method, right?

how to get the data Do you want to know how to set the buffersize parameter of this method?

Also, I noticed a native iOS thread , you are confused about how to get spectrum data, right? I found the code snippets in swift, please see if it is what you want.

private func fft(_ buffer: AVAudioPCMBuffer) -> [[Float]] {
        var amplitudes = [[Float]]()
        guard let floatChannelData = buffer.floatChannelData else { return amplitudes }
 
       
        var channels: UnsafePointer<UnsafeMutablePointer<Float>> = floatChannelData
        let channelCount = Int(buffer.format.channelCount)
        let isInterleaved = buffer.format.isInterleaved
        
        if isInterleaved {
            // deinterleave
            let interleavedData = UnsafeBufferPointer(start: floatChannelData[0], count: self.fftSize * channelCount)
            var channelsTemp : [UnsafeMutablePointer<Float>] = []
            for i in 0..<channelCount {
                var channelData = stride(from: i, to: interleavedData.count, by: channelCount).map{ interleavedData[$0] }
                channelsTemp.append(UnsafeMutablePointer(&channelData))
            }
            channels = UnsafePointer(channelsTemp)
        }
        
        for i in 0..<channelCount {
            
            let channel = channels[i]
           
            var window = [Float](repeating: 0, count: Int(fftSize))
            vDSP_hann_window(&window, vDSP_Length(fftSize), Int32(vDSP_HANN_NORM))
            vDSP_vmul(channel, 1, window, 1, channel, 1, vDSP_Length(fftSize))
            
          
            var realp = [Float](repeating: 0.0, count: Int(fftSize / 2))
            var imagp = [Float](repeating: 0.0, count: Int(fftSize / 2))
            var fftInOut = DSPSplitComplex(realp: &realp, imagp: &imagp)
            channel.withMemoryRebound(to: DSPComplex.self, capacity: fftSize) { (typeConvertedTransferBuffer) -> Void in
                vDSP_ctoz(typeConvertedTransferBuffer, 2, &fftInOut, 1, vDSP_Length(fftSize / 2))
            }
 
          
            vDSP_fft_zrip(fftSetup!, &fftInOut, 1, vDSP_Length(round(log2(Double(fftSize)))), FFTDirection(FFT_FORWARD));
            
          
            fftInOut.imagp[0] = 0
            let fftNormFactor = Float(1.0 / (Float(fftSize)))
            vDSP_vsmul(fftInOut.realp, 1, [fftNormFactor], fftInOut.realp, 1, vDSP_Length(fftSize / 2));
            vDSP_vsmul(fftInOut.imagp, 1, [fftNormFactor], fftInOut.imagp, 1, vDSP_Length(fftSize / 2));
            var channelAmplitudes = [Float](repeating: 0.0, count: Int(fftSize / 2))
            vDSP_zvabs(&fftInOut, 1, &channelAmplitudes, 1, vDSP_Length(fftSize / 2));
            channelAmplitudes[0] = channelAmplitudes[0] / 2 
            amplitudes.append(channelAmplitudes)
        }
        return amplitudes
    }

mc 5,426 Reputation points

2024-12-19T10:01:29.6366667+00:00

I know how to display it but I do not know how to get the AVAudioPCMBuffer
mc 5,426 Reputation points

2024-12-20T00:47:01.5566667+00:00

now I have not find the AVPlayerNode

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mc 5,426 Reputation points

2024-12-19T10:01:29.6366667+00:00

I know how to display it but I do not know how to get the AVAudioPCMBuffer
mc 5,426 Reputation points

2024-12-20T00:47:01.5566667+00:00

now I have not find the AVPlayerNode

Answer 1

Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Microsoft External Staff

Hello,

now I have not find the AVPlayerNode

Please try using AVAudioEngine to play the audio, then fine the AVPlayerNode by visiting the MainMixerNode property. For example, I create a custom player class.

  public class AudioPlayer
  {
      public AVAudioEngine Engine { get; set; } = new AVAudioEngine();
      public AVAudioPlayerNode Player { get; set; }= new AVAudioPlayerNode();
      public AudioPlayer()
      {
          Engine.AttachNode(Player);
          Engine.Connect(Player,Engine.MainMixerNode,null);
          Engine.MainMixerNode.InstallTapOnBus(0, 2048, null, (buffer, when) => {
          });
          Engine.Prepare();
        //  NSError e = new NSError();
       //   Engine.StartAndReturnError(out e);
 
      }         
  }

Best Regards,

Wenyan Zhang

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mc 5,426 Reputation points

2024-12-20T07:42:28.18+00:00

yes it works.

but how to write func fft(_ buffer: AVAudioPCMBuffer) in .net ios?
mc 5,426 Reputation points

2024-12-21T04:20:46.4133333+00:00

and it will slower 1-3seconds when I play it the visualizer will slower than real-time
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Reputation points Microsoft External Staff

2024-12-23T07:17:00.3433333+00:00

Do you customize a visualizer? You could create a new thread with the details, and we can investigate further.

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how to get waveform data when I play music in .net ios?

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